First I'd like to thank
everybody for their congrats on & offline, everybody is still doing fine,
but sleep is still at a premium. Definitely no time for flying :-(, maybe in a
few days. No jump seat in the 9 yet, but
I'm already planning it :-)
Second I need to say that
even though I seem to have found a successful fuel system, I do regret not adding fuel
return fittings in each of my 6 tanks. A simple 1/4" bulkhead fitting with a
cap is not too much $$$, or weight and it will allow simple plumbing changes
if ever necessary. While I have 30 successful flight hours on my
returnless system, it is prudent to remember that I only have 30 flight hours
on my returnless system.:-). And none of this flight time was down south where
your idea of summer & winter are vastly different than up here in the
great white north. At this point I'd recommend that you install return
fittings while it's still easy to do. I wish I had, however if I had I may not
have ever tried this system and only went with a conventional system. Even if
my system continuous to be successful, if I ever have a reason to remove my
tanks, I will add return fittings with caps.
I may have this
opportunity. I currently have capacitive fuel sensors, which are read by an
E.I.sensor. I bought the components to build a converter as per Jim Weirs
plans from a past KitPlanes article, in order to display on the EM2 which
needs a 0-5 volt signal. However I find that auto fuel seems to vary in it's
capacitance. When properly calibrated they are very accurate, but put in fuel
from another batch and the readings are less accurate, put in fuel from the
original batch and they are accurate again. Start adding pre-mix fuel and of
coarse they're inaccurate again. I'm unsure if it is the fuel itself that has
dielectric variations or possibly the dye used to mark the fuel as off-road
use only? I've noticed that the purple colour seems to vary as some batches
seem to have almost no colour while others are very dark.
In any event, while I will still
leave the capacitive probes in place, I think I will order a set of float
resistive sensors to display fuel info on the EM2. If I do this I will add the
return fittings and then possibly I may add an electric fuel tank selector
valve that I have, except that it will be used to select fuel destination
instead of source. In it's normal un-energized state it will continue to
operate as a returnless system, but when energized it will return to a wing
tank. In the event of an unexpected vapour lock, I can just hit a mom-on push
button to return to a wing tank. My concern with this is that these fuel tank
selector valves are meant to be located on the suction side of the fuel pump,
so I'm unsure how well they would work in the return
line.
Bottom line...
Install the return fittings while still it's easy!